Fig. 1: Neuronal activity recruits cAMP–PKA signalling in astrocytes.
From: Adenosine signalling to astrocytes coordinates brain metabolism and function
a, Two-photon (2P) optical recordings of neuronal activity-induced cAMP responses in astrocytes transduced to express Epac-SH187 in hippocampal slices. SC, Schaffer collateral fibres. Scale bar, 20 µm. b, Representative traces and summary data illustrating changes in intracellular [cAMP] ([cAMP]i; Epac-SH187 fluorescence intensity (FI) ratio of mTurquoise2:Venus) in astrocytes of the CA1 area induced by stimulation of Schaffer collateral fibres (burst of 5 pulses at 20 Hz) in control conditions and under conditions of glutamate receptor (GluR) blockade, or in the presence of tetrodotoxin (TTX). c, Representative astrocyte cAMP responses induced by ATP, ATP in the presence of the adenosine A2 receptor antagonist ZM241385, adenosine (ADO) and adenosine in the presence of ZM241385. Images illustrate changes in the Epac-SH187 sensor mTurquoise2 fluorescence in astrocytes in response to ATP. In this sensor, cAMP binding increases mTurquoise2 fluorescence. Scale bar, 20 µm. d, Representative trace showing a significant decrease in the Epac-SH187 sensor signal in hippocampal astrocytes induced by adenosine A2 receptor (A2R) blockade, indicative of a reduction in basal [cAMP]i. e, Summary data showing peak changes in [cAMP]i (Epac-SH187 FI ratio) in astrocytes induced by glutamate, ATP, AMP-PNP and ATP in the presence of the adenylyl cyclase inhibitor SQ22536, the ecto-5′-nucleotidase inhibitor α,β-methylene-ADP, the adenosine receptor inhibitor caffeine or ZM241385. Also shown are peak cAMP responses induced by adenosine. f, Summary data showing changes in [cAMP]i in astrocytes in response to ZM241385, ATP or ATP in the presence of ZM241385, recorded in hippocampal slices. In the box-and-whisker plots, the central dot indicates the mean, the central line indicates the median, the box limits indicate the upper and lower quartiles, and the whiskers extend to 1.5× the interquartile range from the quartiles. In panels b–d, traces show averaged (mean ± s.e.m.) recordings from several individual cells in a representative experiment. In panels b,e,f, the numbers in parentheses indicate the number of individual cells/number of separate slices or cultures prepared from the same number of animals. P values were determined by one-way analysis of variance (ANOVA) followed by Sidak’s post-hoc test.
